Safety lamp



May28, 1946. b, C ADE 2,400,916

SAFETY LAMP Filed Sept. 11, 1944 A, I I! Patented May 28, 1946 SAFETYLAMP Joseph D. Ceader, East Cleveland o hio, assignori to GeneralElectric Company, acorporation of New York Application September 11,1944, Serial No'. 553,517-

1 Claim.

This invention relates to electric safety lamps for the use of minersand others who work where inflammable, explosive, or otherthermo-reactive atmospheres or gases may be encountered. The inventionaims to provide protection against dangeifrom breakage of a lamp bulb bypromptly stopping the flow of current to the lamp. A further aim is toaccomplish this in a simple and convenient way, without necessity forheavy or complicated apparatus; on the contrary, the equipment can bemade very light and compact, and easy and inexpensive to make and use.The invention is applicable to lamps with plural end contacts on theirbases, and to lamps with plural filaments, as well as to the singlefilament, single contact lamps in connection with which it is hereillustrated and particularly explained. Various features and advantagesof the invention will appear from the description of species and formsof embodiment, and from the drawing.

In the drawing, Fig. 1 is a side view of a safety lamp equipmentconveniently embodying the invention, certain parts being partly brokenout and in section; and Fig. 2 is a corresponding end view.

Figs. 3 and 4 are views similar to Figs. 1 and 2 I illustrating amodification.

Fig. 1 shows the invention as embodied in a miners safety lamp equippedwith a known type of fastener I for mounting the lamp on a miners cap(not shown), and with a flexible cable 2 for connecting it to a battery(not shown) that may be carried on the miners back, or to any othersource of current. These parts I, 2 are shown attached to a holder orsocket 3 that includes an external casing or shell 4 provided with aninsulative lining 5 and having mounted therein an insulative part 8 thatcarries screw connectors I, l for lead-wires 8, 8 of the cable 2, aswell as contacts 9, I0 for an electric lamp II. The lamp I I may be anincandescent filament lamp, or a discharge lamp of fluorescent or othertype, or any other suitable electric lamp. As shown, it comprises ashouldered bulb with a parabolic, spherical, or otherwise rounded rearreflector portion I2 and a spherically rounded radiationtransmittingfront portion I3, as well as a neck which provides a mounting orbaseportion I4, or is equipped therewith. Associated with this portion I4 ofthe lamp are contact terminals I5, I6 for coacting with the contactmeans 9, I 0 already mentioned as associated with the holder 3. The lampcontacts shown are a center contact I5 at the end of an insulativeconical projection on the base I4, and an annular contact shoulder I6surrounding this conical projection. The socket contacts shown are aC-bent and somewhat resilient metal strip 9 fixed on the insulative part6 and electrically connected to one of the connectors I, and a helicalmetal wire compression spring Ill accommodated in the shell lining 5around the contact 9 and electrically connected to the other connnector1 by a metal strip I7 set into the part 6. This spring I0 bears againstthe lamp base shoulder I6 and urges the base I4 and its center contactI5 away from the center contact 9 of the socket 3.

For normally holding the lamp II and its base I4 in place in the holderor socket 3, and likewise holding the contacts I5 and 9 together, one ormore retainers or hooks I8 associated with the holder 3 are arranged tohook over suitable shoulder(s) on the lamp bulb: viz., in the devicehere illustrated, over the shouldered front bulb portion I3. As shown inFigs. 1 and 2, three hooks I8 are mounted around the open front end ofthe holder 3 so that they can swing together on the bulb end I3 afterthe bulb has been placed in the holder, or vice-versa. For this purpose,the rear ends of the hooks I8 may be pivoted on a ring [9 fitted into anannular-groove in the forward end of the holder shell 4, behind ashoulder formed by a flare 20 at the mouth of this shell.

To hold the hooks I8 together in engagement with the shouldered bulb endI3, a tie in the form of a springy, resilient wire ring 2| is shownembracing the shanks of the hooks (and the corresponding portion of thebulb), behind the greatest spread of the hooks at the largest diameterof the bulb. To supplement friction in holding the tie ring ZI in place,the shanks of the hooks may have serrations or rounded notches 22 for aring to engage in. The spring of the ring 2|, supplemented by someresilient flexure of the hooks I8, makes it easy to assure a convergentgrip of the hooks on the bulb II with considerable resilient pressure.

So long as the bulb II is intact, the hooks I8 hold it in the positionshown in the holder, with the spring I6 under elastic compressionagainst the base contact I0, and the center contacts I5, 9 engaged. Ifand when the bulb II' is broken, its diminished strength assures itsbeing collapsed and shattered by the force of the spring I6 and theconvergent resilient pressure of the hooks I8. When this happens, thespring I6 is free to push the base I4 outward in the holder or socket 3,separating the contacts I5, 9, breaking the circuit, and stopping theflow of current. The usual gas filling in the lamp II serves to preventcon- 7 tact or the surrounding atmosphere with the electric translationmeans (e. g., filament(s) or electrode(s)) in the lamp bulbuntil theseparts have cooled to the point where there is no further danger ofexplosion or the like. I V v The device illustrated in Figs. 3 and 4:differs from that just described in having only a single hook l8, whichhooks over the front bulb end 13 and bears thereon symmetrically aroundthe bulb axis, having for this purpose a plurality of radial arms orfingers 23. The rear end of this hook I8 is shown as pivoted at 9 tolugs on a collar 24 clamped around the open end of the holder shell 4over an annular shoulder 25 embossed in the shell. When the bulb II hasbeen placed in the holder 3 and the hook l8 swung intoposition'as shown,the pressure of the spring I6 and the bulb ll against the hook l8 andits fingers 23 retains the hook against accidental disengagement as l0ngas the bulb remains intact. When the bulb H is broken, the force of thespring l6 collapses and shatters it and also pushes the base l4 awayfrom the contact 9 and breaks the circuit, etc., just as in the deviceof Figs. 1 and 2.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

In a lamp holder of the type comprising a socket including a shelladapted to receive the base of an electric lamp and containing contactsengageable with contacts on said lamp base, and spring means urging thelamp outwardly of the socket and out of engagement with at least one ofthe sockets contacts, means to retain the lamp in said socket comprisinga plurality of hookshaped fingers pivotally supported from said shell attheir rearward ends to hook over the front end of the bulb of said lampto retain the lamp in the socket, and resilient ti means embracing thebulb and said fingers to hold said finger in closed position around saidbulb.

JOSEPH D. CEADER.

